These cars come in economy / budget categories, with engine oil sumps ranging from, generally speaking, 2.5~4.5L capacities (for 660cc to 2500~3000 cc engines, just a rough idea). These are not big, luxury vehicles or full size Sedans, having engine oil sumps from 8 to 13L capacities, and engine cc from 4000~8000 cc, or even more.
In such vehicles, drain interval can be from 10~15,000 Kms, and OEM can say to simply top-up in between, if oil level drops (their oil filters are also designed in ways to last 10~15,000 Kms easily).
But applying the same philosophy on a 660 cc engine car; with oil sump capacity of merely 2.2~2.6L (depending), I can only pray.
Even if the oil filter is designed to last 10,000 Kms, engine oil can start deteriorating after 5,000 Kms, as it cannot take that much beating.